Fun with Fomites - Do you see a pattern in the size and amount of colonies in each plate?

You probably got the most colony growth in section 1 of each plate that grew any bacteria. The number of colonies in each of the four sections of the plates likely decreased from section 1 to 4. This is because each time you swabbed a section of the plate, there were fewer bacterial cells remaining on your cotton swab. So by the time you swabbed section 4, there were only a few cells left to get onto the plate and grow into colonies. Why do microbiologists swab petri plates this way? Because they want to grow individual colonies separated by space from other nearby colonies. By examining the shape and color of these individual colonies, they can tell certain things about the bacteria, such as what type they are, whether they're normal or mutated, etc.

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